1. Field of the Invention
The present invention is directed to an ultrasound transducer arrangement having an electroacoustical transducer part to which at least one acoustic matching layer is allocated.
2. Description of the Prior Art
Matching layers are employed in ultrasound technology in order to reduce reflections outside an examination subject at boundary surfaces between two materials having different impedance, or to transmit the ultrasound energy from the transducer part into the examination subject and back with as little loss as possible. To that end, at least one matching layer is arranged between the two materials. For example, matching layers are employed for acoustic matching of an electroacoustic transducer part to an examination subject. In addition, an acoustic sump or damping member having at least one matching layer can be adapted to the transducer part.
U.S. Pat. No. 4,717,851 discloses an ultrasound transducer arrangement of this type. For acoustic matching of the electroacoustic transducer part to an examination subject or to an acoustic propagation medium, matching layers are arranged in the sound propagation path, their acoustic impedance lying between that of the transducer part and that of the examination subject or propagation medium. Matching layers composed of a synthetic resin such as, for example, epoxy resin, wherein superfine particles of a mineral or metallic material are imbedded, are standard. The acoustic impedance of the matching layer is thereby essentially set by the quantity and the material of the added particles. A uniform distribution of the particles in the synthetic resin, however, cannot always be achieved over larger volume regions. As a result, the reproduceability of the function-determining acoustic properties is limited. Moreover, inhomogeneities and voids must be accepted under certain circumstances. Such matching layers are electrically non-conductive; the transducer part must therefore be additionally electrically contacted and/or shielded.
European Application 0 031 049 discloses an acoustic transducer arrangement for testing materials that is suitable for employment at high temperatures. The transducer arrangement includes a lead part composed of a metallic member having high specific attenuation. A sintered metal is proposed as the material for this member. The high specific attenuation is thereby decisively influenced by the porosity. A high specific attenuation, however, is undesirable in acoustic matching layers, particularly in medical applications.